Extended COB-USB With Dual-Personality Contacts

ABSTRACT

A dual-personality extended USB (EUSB) system supports both USB and EUSB memory cards using an extended 9-pin EUSB socket. Each EUSB memory card includes a PCBA having four standard USB metal contact pads disposed on an upper side of a PCB, and several extended purpose contact springs that extend through openings defined in the PCB. Passive components are mounted on a lower surface of the PCB using SMT methods, and IC dies are mounted using COB methods, and then the components and IC dies are covered by a plastic molded housing. The extended 9-pin EUSB socket includes standard USB contacts and extended use contacts that communicate with the PCBA through the standard USB metal contacts and the contact springs. The PCBA includes dual-personality electronics for USB and EUSB communications.

RELATED APPLICATIONS

This application is a continuation-in-part (CIP) of U.S. Patentapplication for “MOLDING METHODS TO MANUFACTURE SINGLE-CHIPCHIP-ON-BOARD USB DEVICE”, U.S. application Ser. No. 11/773,830, filedJul. 5, 2007, which is a CIP of “Single-Chip Multi-Media Card/SecureDigital (MMC/SD) Controller Reading Power-On Boot Code from IntegratedFlash Memory for User Storage”, U.S. application Ser. No. 11/309,594,filed Aug. 28, 2006, which is a CIP of “Single-Chip USB ControllerReading Power-On Boot Code from Integrated Flash Memory for UserStorage”, U.S. application Ser. No. 10/707,277, filed Dec. 2, 2003, nowU.S. Pat. No. 7,103,684.

This application is also a continuation-in-part (CIP) of U.S. Patentapplication for “Extended USB Dual-Personality Card Reader” U.S.application Ser. No. 11/927,549, filed Oct. 29, 2007.

FIELD OF THE INVENTION

This invention relates to portable electronic devices, and moreparticularly to portable electronic devices with ExpandedUniversal-Serial-Bus (EUSB) connections.

BACKGROUND OF THE INVENTION

Universal-Serial-Bus (USB) has been widely deployed as a standard busfor connecting peripherals such as digital cameras and music players topersonal computers (PCs) and other devices. Currently, the top transferrate of USB is 480 Mb/s, which is quite sufficient for mostapplications. Faster serial-bus interfaces are being introduced toaddress different requirements. PCI Express, at 2.5 Gb/s, and SATA, at1.5 Gb/s and 3.0 Gb/s, are two examples of high-speed serial businterfaces for the next generation devices, as are IEEE 1394 and SerialAttached Small-Computer System Interface (SCSI).

FIG. 26(A) shows a prior-art peripheral-side USB connector. USBconnector 10 may be mounted on a board in the peripheral. USB connector10 can be mounted in an opening in a plastic case (not shown) for theperipheral.

USB connector 10 contains a small connector substrate 14, which is oftenwhite ceramic, black rigid plastic, or another sturdy substrate.Connector substrate 14 has four or more metal contacts 16 formedthereon. Metal contacts 16 carry the USB signals generated or receivedby a controller chip in the peripheral. USB signals include power,ground, and serial differential data D+, D−.

USB connector 10 contains a metal case that wraps around connectorsubstrate 14. The metal case touches connector substrate 14 on three ofthe sides of connector substrate 14. The top side of connector substrate14, holding metal contacts 16, has a large gap to the top of the metalcase. On the top and bottom of this metal wrap are formed holes 12. USBconnector 10 is a male connector, such as a type-A USB connector.

FIG. 26(B) shows a female USB connector. Female USB connector 20 can bean integral part of a host or PC, or can be connected by a cable.Another connector substrate 22 contains four metal contacts 24 that makeelectrical contact with the four metal contacts 16 of the male USBconnector 10 of FIG. 26(A). Connector substrate 22 is wrapped by a metalcase, but small gaps are between the metal case and connector substrate22 on the lower three sides.

Locking is provided by metal springs 18 in the top and bottom of themetal case. When male USB connector 10 of FIG. 26(A) is flipped over andinserted into Female USB connector 20 of FIG. 26(B), metal springs 18lock into holes 12 of male USB connector 10. This allows the metalcasings to be connected together and grounded.

Other bus interfaces offer higher transfer rates than USB devices, whichhave a top transfer rate of 480 Mb/s. For example,Peripheral-Component-Interconnect (PCI) Express (2.5 Gb/s) andSerial-Advanced-Technology-Attachment (SATA) (1.5 Gb/s and 3.0 Gb/s) aretwo examples of high-speed serial bus interfaces for next generationdevices. IEEE 1394 (Firewire) supports 3.2 Gb/s. Serial AttachedSmall-Computer System Interface (SCSI) supports 1.5 Gb/s. These highspeed interfaces renders standard USB devices undesirable for someapplications.

What is needed is a flexible system that supports both standardUniversal-Serial-Bus (USB) devices and high speed USB devices using asingle dual-personality socket.

SUMMARY OF THE INVENTION

The present invention is directed to a dual-personality memory systemthat supports both standard USB 2.0 devices and high speed extended USB(EUSB) devices. A host side of the dual-personality memory systemincludes a multiple pin (e.g., nine-pin) USB female socket that issimilar to a standard female USB socket, but in addition to the standard(four) USB contact pins utilized to facilitate communications withstandard USB 2.0 devices, the extended multiple pin USB socket includesone or more additional rows of contacts that facilitate extendedcommunications (i.e., including additional transmitting/receivingdifferential pairs) between the host system and dual personality“extended” USB (EUSB) devices (e.g., memory cards). Each EUSB memorycard includes both standard USB contacts, a second row of extendedfunction contacts, and a special controller that facilitatescommunication with a host system using either the standard serial USBcommunication protocol using the four standard USB contacts (e.g., whenthe EUSB memory card is plugged into a “standard” USB female socket), orextended communications using both the standard contacts and the secondrow of contacts (e.g., when the EUSB memory card is plugged into themultiple pin USB female socket of a dual-personality memory system).

The present invention is particularly directed to the EUSB memory cardincluding both standard USB metal contacts and a row of metal contactsprings that extend from the EUSB memory card in a way that facilitatesreliable extended (e.g., nine bit) communications. The EUSB memory cardincludes a printed circuit board assembly (PCBA) including at least onedual-personality communication integrated circuit (IC) mounted on alower surface of the PCB, four standard USB fixed contacts disposed onan upper surface of the PCB near the PCB's front edge, and several(e.g., five) metal contact springs positioned behind the standard USBcontacts. In accordance with an aspect of the invention, the PCB isformed with parallel slots (openings) that are disposed behind thestandard USB contacts, and the metal contact springs are mounted suchthat a portion of each metal contact spring extends through acorresponding slot such that a contact portion of each contact springprotrudes above the upper PCB surface. A dual-personality communicationIC is configured to selectively communicate either with a standard USBhost system by way of the standard USB contacts (only), or with adual-personality flash memory card system by way of all (e.g., nine)contact pads/springs. By forming the contact springs such that theyextend through the slots and protrude above the PCB surface, the contactsprings are provided with sufficient tolerance to both reliably contactcorresponding contact pads of a host female socket, and are also able tobend downward (i.e., into the PCB) when the contact springs are pressedagainst the corresponding contact pads of a host female socket.

In accordance with an embodiment of the present invention, the EUSBmemory card is manufactured by forming a contact spring assembly inwhich the contact springs are mounted on a base (e.g., a PCB or plastic)substrate, and the assembly is then mounted onto the device PCB suchthat the springs protrude through the parallel slots (openings) definedin the PCB. The PCB includes standard USB contacts formed on its uppersurface between its front edge and the row of slots, and contact padsformed on its lower PCB surface for mounting one or more ICs and passivecomponents. According to an aspect of the invention, the spring assemblyis mounted onto the lower surface of the PCB such that each contactspring extends through a corresponding slot such that a contact portionthereof protrudes from the upper PCB surface, and such that the basecovers the slots during a subsequent plastic molding step. By formingthe PCBA in this manner, the springs are quickly and reliably mountedonto the PCB, and the base of the spring assembly covers the slots. ThePCBA is then placed in a mold cavity, and a single-piece molded housingis formed such that all the ICs and passive components are encased bythe plastic molded housing and the upper surface of the PCB is exposed.Note that the base serves to prevent molten plastic from entering theopenings and covering the contact springs, which could prevent properoperation of the EUSB memory card. The resulting EUSB memory card formsa modular structure including a connector plug with the standard USBmetal contact pads and the contact springs being arranged such that,when said connector plug is inserted into said extended multiple pin USBsocket, each of the standard USB contact pads contacts a correspondingstandard USB contact of the extended multiple pin USB socket, and eachof the contact springs contacts a corresponding dual-personality contactof the extended multiple pin USB socket. By forming the EUSB memory cardin this manner, final assembly of the EUSB memory card into any ofseveral external housings is greatly simplified, which reducesmanufacturing costs by simplifying the assembly process.

According to an aspect of the invention, passive components are mountedonto the PCB using one or more standard surface mount technology (SMT)techniques, and one or more unpackaged IC die (e.g., thedual-personality communication IC die and a flash memory die) aremounted using chip-on-board (COB) techniques. During the SMT process,the SMT-packaged passive components (e.g., capacitors, oscillators, andlight emitting diodes) are mounted onto contact pads disposed on thePCB, and then known solder reflow techniques are utilized to connectleads of the passive components to the contact pads. During thesubsequent COB process, the IC dies are secured onto the PCB using knowdie-bonding techniques, and then electrically connected to correspondingcontact pads using, e.g., known wire bonding techniques. After the COBprocess is completed, the housing is formed over the passive componentsand IC dies using plastic molding techniques. By combining SMT and COBmanufacturing techniques to produce modular USB core components, thepresent invention provides several advantages over conventionalmanufacturing methods that utilize SMT techniques only. First, byutilizing COB techniques to mount the USB controller and flash memory,the large PCB area typically taken up by SMT-packaged controllers andflash devices is dramatically reduced, thereby facilitating significantminiaturization of the resulting footprint (i.e., providing a shorterdevice length and thinner device width). Second, the IC die height isgreatly reduced, thereby facilitating stacked memory arrangements thatgreatly increase memory capacity of the EUSB memory cards withoutincreasing the EUSB memory card footprint. Further, overallmanufacturing costs are reduced by utilizing unpackaged controllers andflash devices (i.e., by eliminating the cost associated with SMT-packagenormally provided on the controllers and flash devices). Moreover, themolded housing provides greater moisture and water resistance and higherimpact force resistance than that achieved using conventionalmanufacturing methods. Therefore, the combined COB and SMT methodaccording to the present invention provides a less expensive and higherquality (i.e., more reliable) memory product with a smaller size thanthat possible using conventional SMT-only manufacturing methods.

According to an embodiment of the present invention, the EUSB memorycard is disposed in a plastic molded external housing so as to form adevice assembly including a standard USB metal plug shell and a cover.By forming the EUSB memory card in the manner described above, thepresent invention greatly simplifies the assembly process utilized toform the device assembly, thus reducing overall costs.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects and advantages of the presentinvention will become better understood with regard to the followingdescription, appended claims, and accompanying drawings, where:

FIGS. 1(A), 1(B), 1(C) are perspective top, cross sectional side andcross sectional side views, respectively, showing a dual-personality USBmemory system including an EUSB memory card according to a simplifiedembodiment of the present invention;

FIG. 2 is a simplified block diagram showing a host system of thedual-personality USB memory system of FIG. 1;

FIGS. 3(A) and 3(B) are exploded perspective and assembled perspectiveviews showing an EUSB memory card according to a specific embodiment ofthe present invention;

FIG. 4 is a flow diagram depicting a method for producing the extendedUSB dual-personality extended USB memory card of FIG. 3(A) according toanother embodiment of the present invention;

FIGS. 5(A) and 5(B) are top perspective and partial top perspectiveviews showing a PCB panel utilized in the method of FIG. 4;

FIGS. 6(A) and 6(B) are bottom perspective and partial bottomperspective views showing the PCB panel of FIG. 5(A);

FIGS. 7(A) and 7(B) are exploded perspective and assembled perspectiveviews showing a contact spring assembly utilized in the method of FIG. 4according to an embodiment of the present invention;

FIGS. 8(A) and 8(B) are top perspective and bottom perspective viewsdepicting mounting of the contact spring assembly of FIG. 7(B) onto thePCB panel of FIG. 5(A) according to an embodiment of the presentinvention;

FIGS. 9(A) and 9(B) are bottom perspective and partial bottomperspective views showing the PCB panel of FIG. 5(A) after the contactspring assembly of FIG. 7(B) is mounted thereon;

FIGS. 10(A) and 10(B) are top perspective and partial top perspectiveviews showing the PCB panel of FIG. 5(A) after the contact springassembly of FIG. 7(B) is mounted thereon;

FIGS. 11(A) and 11(B) partial bottom perspective and bottom perspectiveviews showing the PCB panel of FIG. 10(A) during a subsequent SMTprocess;

FIGS. 12(A), 12(B), 12(C) and 12(D) are simplified perspective andcross-sectional side views depicting a semiconductor wafer and a processof grinding and dicing the wafer to produce IC dies utilized in themethod of FIG. 4;

FIGS. 13(A) and 13(B) are partial bottom perspective and bottomperspective views depicting a die bonding process utilized to mount theIC dies of FIG. 12(D) onto the PCB panel of FIG. 11(B) according to themethod of FIG. 4;

FIGS. 14(A) and 14(B) are partial bottom perspective and bottomperspective views depicting a wire bonding process utilized to connectthe IC dies to corresponding contact pads disposed on the PCB of FIG.13(B) according to the method of FIG. 4;

FIGS. 15(A) and 15(B) are simplified cross-sectional side viewsdepicting a molding process for forming a molded housings over the PCBpanel of FIG. 14(B) according to the method of FIG. 4;

FIG. 16 is a top perspective views showing the PCB panel of FIG. 15(B)after being removed from its mold;

FIG. 17 is a cross-sectional side view showing a singulation processaccording to the method of FIG. 4;

FIG. 18 is an exploded perspective view showing a EUSB following amarking process according to an embodiment of the present invention;

FIG. 19 is a block diagram showing a dual-personality controller circuitof a EUSB memory card according to an embodiment of the presentinvention;

FIG. 20 is simplified cross-sectional side view showing an EUSB memorycard including stacked-memory according to another embodiment of thepresent invention;

FIG. 21 is simplified cross-sectional side view showing a single-chipEUSB memory card according to another embodiment of the presentinvention;

FIG. 22 is an exploded perspective view showing an EUSB assemblyaccording to another embodiment of the present invention;

FIG. 23 is an exploded perspective view showing the EUSB assembly ofFIG. 22 in a partially assembled state;

FIG. 24 is an exploded perspective view showing a cap of the EUSBassembly of FIG. 22 in additional detail;

FIG. 25 is perspective view showing the EUSB assembly of FIG. 22 in afully assembled state; and

FIGS. 26(A) and 26(B) are front perspective views showing a conventionalUSB male plug and a conventional USB female socket, respectively.

DETAILED DESCRIPTION OF THE DRAWINGS

The present invention relates to an improved method for manufacturingextended USB (EUSB) devices (e.g., memory cards), and in particular toEUSB devices (memory cards) manufactured by the method. The followingdescription is presented to enable one of ordinary skill in the art tomake and use the invention as provided in the context of a particularapplication and its requirements. As used herein, the terms “upper”,“upwards”, “lower”, “downward”, “front” and “back” are intended toprovide relative positions for purposes of description, and are notintended to designate an absolute frame of reference. Variousmodifications to the preferred embodiment will be apparent to those withskill in the art, and the general principles defined herein may beapplied to other embodiments. Therefore, the present invention is notintended to be limited to the particular embodiments shown anddescribed, but is to be accorded the widest scope consistent with theprinciples and novel features herein disclosed.

FIGS. 1(A), 1(B) and 1(C) show a dual-personality USB memory system 100including an extended 9-pin (multiple pin) USB female socket 190 thatcommunicates with both standard USB memory cards and dual-personalityextended USB (EUSB) memory cards 101 that are manufactured and operatein accordance with the present invention. That is, in accordance withthe exemplary embodiment, dual-personality USB memory system 100 isoperated to process (receive and transmit) both standard USB 2.0 (fourpin) signals and extended function signals through extended 9-pin USBsocket 190 in a manner consistent with that described in co-owned U.S.Pat. No. 7,108,560, entitled “Extend USB Protocol Plug and Receptaclefor implementing Single-Mode Communication”, which is incorporatedherein by reference in its entirety. In particular, in accordance withthe 9-pin embodiment disclosed herein, in additional to the fourstandard USB 2.0 signals (i.e., power, ground, D+and D−), the extra fivecontact springs are utilized to transmit and additional ground (e.g.,using the middle spring), a transmitting differential pair (T+ and T−),and a receiving differential pair (R+and R−) using the left and rightside contact spring pairs, respectively. Thus the term “extended USB”(EUSB) is used herein to mean at least one transmitting/receiving signalpair in addition to the four standard USB signals. With the additionalof these signal pairs, transmitting/receiving modes can be executedconcurrently without the wait state of transmitting on receiving tocomplete, and vice versa, thereby significantly enhancing communicationspeeds.

Referring to the right side of FIG. 1(A) and FIG. 1(B), EUSB memory card101 generally includes a printed circuit board assembly (PCBA) 110 and asingle-piece molded plastic housing 150. PCBA 110 includes a printedcircuit board (PCB) 111 having opposing upper (first) surface 116 and anopposing lower (second) surface 118, and includes a handle (rear)portion 112 and a male plug (front portion) connector 114. According toan aspect of the present invention, male plug connector 114 includesfour standard USB (metal) contacts 121 (disposed on upper surface 116 inaccordance with standard techniques, and five extended-use (metal)contact springs 122 disposed such that portions thereof extend throughslots (openings 115) defined in PCB 111, and arranged in a row behindstandard USB contacts 121. A dual-personality communication integratedcircuit (IC) 131 is mounted on lower surface 118, and conductive traces(not shown) are formed on PCB 111 using known techniques such thatcontacts 121 and 122 are connected to dual-personality communication IC131. In addition, a memory (e.g., flash) IC 135 is mounted on lowersurface 118 and connected to dual-personality communication IC 131 andcontacts 121 and 122 by conductive traces (not shown). Other featuresand details associated with extended USB memory card 101 are providedbelow.

Because many conventional USB (male) connectors and (female) sockets(also referred to as standard USB plug connectors and standard USBsockets herein) are widely deployed, it is advantageous for the improvedextended USB connector to be compatible with standard USB sockets, andan extended USB socket to be compatible with standard USB connectors forbackward compatibility. Although the height and width of USBconnectors/sockets have to remain the same for insertion compatibility,the length of each may be extended to fit additional metal contacts foradditional signals. Furthermore, additional metal contacts (pins orsprings) may be disposed on the plug connector, either adjacent toopposite the existing four standard USB metal contacts. As indicated inFIG. 1(A), plug connector 114 of EUSB memory card 101 represents suchextended plug connector that includes the four standard USB metalcontact pads 121 and the five additional (extended-use) contact springs122 that are disposed in a row behind standard USB metal contact pads121.

Referring to FIG. 1(B), to support communications with EUSB memory card101, extended 9-pin USB female socket 190 includes four standard USBmetal contact pins 191 and five additional (dual-personality) contactpads 192 that are disposed on the bottom surface of a pin substrate 194to engage standard USB metal contact pads 121 and additional contactsprings 122 when plug connector 114 is inserted therein. Female socket190 also includes an outer (e.g., metal) casing 196 that cooperates withsubstrate 194 to define a cavity (slot) 197 for receiving plug connector114. FIG. 1(B) shows plug connector 114 inserted into 9-pin USB socket190 such that standard USB metal contact pins 191 of socket 190 contactstandard USB metal contacts 121 of extended USB memory card 101, andadditional contact pads 192 of socket 190 contact additional contactsprings 122 of extended USB memory card 101, thereby facilitating 9-pincommunication between extended USB memory card 101 and a host systemcontroller (not shown) that is connected to socket 190.

As indicated in FIGS. 1(B) and 1(C), each contact spring 122 extendsthrough a corresponding opening 115 and protrudes above upper surface116 by an amount that is sufficient to reliably contact correspondingcontact pads 192 when EUSB memory card 101 is inserted into host femalesocket 190. That is, each metal contact spring 122 includes a baseportion 123 that is disposed on the lower side of PCB 111, and includesa contact portion 124 that protrudes through its corresponding opening(slot) 115 and extends above upper surface 116. Each metal contactspring 122 is connected to at least one of dual-personalitycommunication IC 131 and memory IC 135 by corresponding conductivetraces (not shown). FIG. 1(B) shows EUSB memory card 101 partiallyinserted into host female socket 190, and shows that a lower surface ofcontact pad 192 (indicated by dashed line arrow A) is below the upperpoint of contact portion 124, whereby when EUSB memory card 101 is fullyinserted (as shown in FIG. 1(C)), contact portion 124 reliably contactscontact pad 192, and contact spring 122 bends downward slightly intoopening 115. By forming each contact spring 122 in this manner, contactportion 124 is provided with sufficient tolerance (i.e., extends farenough above upper surface 116) to assure contact with correspondingcontact pad 192, and the ability to flex downward when such contactoccurs, thereby providing a suitable design variance that producesreliable connection between extended-USB socket 190 and EUSB memory card101.

FIG. 2 is a block diagram of an exemplary host system 105 with oneembodiment of extended-USB socket 190 that supports extended-modecommunication. Although the description below refers only tocommunications with standard USB memory cards 60 and EUSB memory card101, those skilled in the art will recognize that the sockets andextended USB memory card features described herein can be altered toaccommodate one or more of a variety of other flash memory devices(e.g., SD, MMC, SATA, PCI-Express, Firewire IEEE 1394, orSerial-Attached SCSI). As shown in FIG. 2, host system 105 includes aprocessor 106 for executing programs including USB-management andbus-scheduling programs. Dual-personality serial-bus interface 107processes data from processor 106 using two protocol processorsincluding a standard USB protocol processor 109A and an EUSB protocolprocessor 109B. USB processor 109A processes data using the USBprotocol, and inputs and outputs USB data on the four standard USBcontacts 191 in extended USB socket 190 (which communicate with standardUSB metal contacts 121 of an inserted standard USB memory card 60 orEUSB memory card 101). In contrast, the extended metal contact pins 192of extended USB socket 190 (which communicate with contact springs 122of EUSB memory card 101, when inserted therein) are connected todual-personality bus switch 107. Transceivers in dual-personality busswitch 107 buffer data transmitted and received as pairs of differentialsignals sent over data lines connected to the extended metal contacts tofacilitate the EUSB protocol. When an initialization routine executed byprocessor 106 determines that inserted flash memory device supports theEUSB protocol, personality selector 108 configures dual-personality busswitch 107 to connect extended USB socket 190 to EUSB processor 109B.Processor 106 communicates with EUSB processor 109B instead of USBprocessor 109A when extended mode is activated. Additional detailsregarding the operation of host 105 will be apparent to those skilled inthe art based on the teachings in U.S. Pat. No. 7,108,560 (cited above)and the description provided below.

FIGS. 3(A) and 3(B) are exploded perspective and assembled perspectiveviews showing a simplified EUSB memory card 101A that is producedaccording to a simplified specific embodiment of the present invention.As set forth below, and with reference to the flow diagram of FIG. 4,EUSB memory card 101A is manufactured by forming a contact springassembly 120 in which contact springs 122 are mounted on a base (e.g., aPCB or plastic) substrate 125, and spring assembly 120 is then mountedonto PCB 111 such that contact portions 124 of each contact spring 122protrude through corresponding openings 115, whereby base 125 coversopenings 115 during a subsequent plastic molding step (described below)that is used to form single-piece molded housing 150.

Similar to the general embodiment described above with reference toFIGS. 1(A) and 1(B), EUSB memory card 101A includes a PCBA 110 made upof a PCB 111 with standard USB contacts 121 formed on its upper surface116 between front edge 111P-1 and the row of openings 115, and one ormore ICs 130 (e.g., dual-personality communication IC 131 and memory IC135) and passive components 140 mounted on lower PCB surface 118. PCB111 is formed in accordance with known PCB manufacturing techniques suchthat metal contacts 120, IC dies 130, and passive components 140 areelectrically interconnected by a predefined network including conductivetraces and other conducting structures that are sandwiched betweenmultiple layers of an insulating material (e.g., FR4) and adhesive. Forexample, contact pads 119-1 and 119-2 are disposed on lower surface 118and used to connect dual-personality communication IC 131 and memory IC135, respectively, using methods described below. Contact pads 119-3 arealso provided on lower surface 118, and used to facilitate the mountingof passive components 140, as described in additional detail below.

As indicated in FIG. 3(A), according to an aspect of the presentinvention, spring assembly 120 is mounted onto lower surface 118 of thePCB 111 such that each contact spring 122 extends through acorresponding opening 115 such that a contact portion 124 of eachcontact spring 122 protrudes from the upper PCB surface 116 in themanner described above with reference to FIG. 1(B). In one embodiment,each contact spring 120 is a substantially C-shaped spring structurehaving a pair of base portions 123 that are secured to a substrate 125,and a central contact portion 124 that forms an arched (bent) structureextending between base portions 123. By forming the PCBA in this manner,when spring assembly 120 is mounted onto lower surface 118, contactportions 124 extend a suitable distance above upper surface 116, andsubstrate 125 covers openings 115. As described in further detail below,PCBA 110 is then placed in a mold cavity, and a single-piece moldedhousing 150 is formed over lower surface 118 such that ICs 130 andpassive components 140 are encased by plastic molded housing 150, andupper surface 116 of PCB 111 is exposed, thereby exposing standard USBcontacts 121 and contact springs 122. By forming EUSB memory card 101Ain this manner, final assembly of the EUSB memory card into any ofseveral external housings (see example below) is greatly simplified,which reduces manufacturing costs by simplifying the assembly process.

Housing 150 is molded plastic formed and arranged such thatsubstantially all of the plastic used to form housing 150 is locatedbelow (i.e., on one side of) PCB 111. As indicated in FIG. 3(B), housing150 includes a peripheral surface 151 extending downward (i.e.,perpendicular to PCB 111), and a lower surface 152 that extends parallelto PCB 111. For discussion purposes, the portion of peripheral surface151 surrounding handle section 112 of PCB 111 is referred to below ashandle surface section 151-1, and the section of peripheral surface 151surrounding plug section 114 of PCB 111 is referred to below as plugsurface section 151-2. Similarly, the portion of lower surface 152covering handle section 112 of PCB 111 is referred to below as handlesurface section 152-1, and the section of lower surface 152 coveringplug section 114 of PCB 111 is referred to below as plug cover section152-2.

Referring to FIG. 3(A), according to another aspect of the invention,passive components 140 are mounted onto lower surface 118 of PCB 111using one or more standard surface mount technology (SMT) techniques,and one or more unpackaged IC dies 130 are mounted on PCB 111 usingchip-on-board (COB) techniques. During the SMT process, passivecomponents 140, such as resistors, capacitors, and oscillator aremounted onto associated contact pads 119-3 disposed on lower surface118, and are then secured to the contact pads using known solder reflowtechniques. To facilitate the SMT process, each of the passivecomponents is packaged in any of the multiple known (preferablylead-free) SMT packages (e.g., ball grid array (BGA) or thin smalloutline package (TSOP)). In contrast, IC dies 130 are unpackaged,semiconductor “chips” that are mounted onto surface 118 and electricallyconnected to corresponding contact pads using known COB techniques.Passive components 140, IC dies 131 and 135 and metal contacts 121 and122 are operably interconnected by way of metal traces that are formedon and in PCB 111 using known techniques.

Referring to FIG. 3(B), a thickness T1 and width W1 of connector plug114 is selected to produce a secure (snug) fit inside either an externalcase (discussed below) or directly into socket 190 (see FIG. 1).According to another aspect of the present invention, housing 150includes a planar lower surface 152 that is parallel to PCB 111, anddefines a single plane such that a first thickness T1 of connector plug114 (i.e., measured between upper PCB surface 116 and the planar lowersurface 152 adjacent to metal contacts 121) is substantially equal to asecond thickness T2 adjacent a rear end of handle section 114. That is,as indicated in FIG. 3(B), modular USB core component 102 issubstantially flat along its entire length (i.e., from rear edge 151-1Ato front edge 151-1B). The term “substantially flat” is meant toindicate that planar surface 152 is substantially parallel to anuppermost surface of modular USB core component 102 along its entirelength. In the embodiment shown in FIG. 3(B), the uppermost surface ofEUSB memory card 101 is defined by upper surface 116 of PCB 111, whichis parallel to planar surface 152 along the entire length of USB corecomponent 102. Similarly, the term “substantially flat” is also intendedto cover embodiments in which the housing includes a thin wall structurethat is formed on or otherwise contacts the upper surface of the PCB. Inthese embodiments, the thickness T2 of handle structure 102 may differby a small amount (e.g., 5%) from thickness T1 of plug structure 105.

According to an aspect of the present invention, the “flatness”associated with modular USB core component 102 is achieved by mountingall of the IC dies (“chips”) and other electronic components of modularUSB core component 102 on lower surface 118 of PCB 111 (i.e., on theside opposite to metal contacts 121). That is, the minimum overallthickness of modular USB core component 102 is determined by thethickness T1 that is required to maintain a snug connection betweenconnector plug 114 and female USB socket connector 190 (see FIG. 1).Because this arrangement requires that metal contacts 121 be located atthe uppermost surface, and that plug wall section 151-2 plug and coversection 152-2 extend a predetermined distance below PCB 111 to providethe required thickness T1. Thus, the overall thickness of modular USBcore component 102 can be minimized by mounting the IC dies 130 and 135and passive components (e.g., capacitor 142) only on lower surface 118of PCB 111. That is, if the IC dies and passive components are mountedon upper surface 116, then the overall thickness of the resulting USBstructure would be the required thickness T1 plus the thickness that theICs extend above PCB 111 (plus the thickness of a protective wall, ifused).

According to another aspect associated with the embodiment shown in FIG.3(B), upper surface 116 of PCB 111 is entirely exposed on the uppersurface of EUSB memory card 101, thus facilitating the production ofEUSB memory card 101 with a maximum thickness equal to thickness T1 ofplug portion 114. That is, because metal contacts 121 are formed onupper surface 116, and upper surface 116 defines the higher end ofrequired plug structure thickness T1, the overall height of EUSB memorycard 101 can be minimized by exposing upper surface 116 (i.e., by makingany point on upper PCB surface 116 the uppermost point of EUSB memorycard 101). As indicated in FIG. 3(B), in accordance with featurespecifically associated with EUSB memory card 101, peripheral wall 151extends around up to but does not cover the peripheral side edges of PCB111 (e.g., front edge 151-2 and rear edge 151-1 extend up to PCB 111,but edges 111P remain exposed). In an alternative embodiment (notshown), an upper edge of peripheral wall 151 may extend over theperipheral edge of PCB 111 to help prevent undesirable separation ofPCBA 110 from housing 150.

FIG. 4 is a flow diagram showing a method for producing an EUSB memorycard according to another embodiment of the present invention.Summarizing the novel method, a PCB panel is fabricated includingmultiple PCBs, each PCB defining openings (block 210; described belowwith reference to FIGS. 5 and 6). Contact springs are then mounted ontothe PCB panel such that each contact spring extends through acorresponding opening and contact portions of each contact springprotrude above the upper surface of the PCB (block 220; described belowwith reference to FIGS. 7-10). ICs and passive components are thenattached to the PCBs (block 225-245; described below with reference toFIGS. 11-14), and then a single-piece molded housing is formed on thePCB such that the passive components and ICs are covered, and such thatsubstantially all of the PCB's upper surface is exposed.

According to another aspect of the invention, the passive components arethen mounted on the PCB panel using SMT techniques (block 225), and thenunpackaged IC dies are die bonded and wire bonded onto the PCB panelusing COB techniques (block 240). Plastic molding is then performed toform single-piece over the PCB panel (block 260), which is thensingulated into individual EUSB memory cards (block 260). This portionof the method provides several advantages over conventionalmanufacturing methods that utilize SMT techniques only. First, byutilizing COB techniques to mount the USB controller and flash memory,the large amount of space typically taken up by these devices isdramatically reduced, thereby facilitating significant miniaturizationof the resulting EUSB memory card footprint. Second, by implementing thewafer grinding methods described below, the die height is greatlyreduced, thereby facilitating stacked memory arrangements such as thosedescribed below. The molded housing also provides greater moisture andwater resistance and higher impact force resistance than that achievedusing conventional manufacturing methods. In comparison to the standardUSB memory card manufacturing that used SMT process, it is cheaper touse the combined COB and SMT (plus molding) processes described hereinbecause, in the SMT-only manufacturing process, the bill of materialssuch as Flash memory and the EUSB controller chip are also manufacturedby COB process, so all the COB costs are already factored into thepackaged memory chip and controller chip. Therefore, the combined COBand SMT method according to the present invention provides a lessexpensive and higher quality (i.e., more reliable) extended USB memorycard product with a smaller size than that possible using conventionalSMT-only manufacturing methods.

Referring to the lower end of FIG. 4, the EUSB memory cards are marked(block 270), and then tested and shipped (block 280). Optional finalassembly is then performed by producing/procuring an external housing,and mounting an EUSB memory card into the external housing.

The flow diagram of FIG. 4 will now be described in additional detailbelow with reference to the following figures.

Referring to the upper portion of FIG. 4, the manufacturing methodbegins with filling a bill of materials including producing/procuringPCB panels (block 210), producing/procuring passive (discrete)components (block 212) such as resistors, capacitors, diodes, LEDs andoscillators that are packaged for SMT processing, producing springassemblies (block 218), and producing/procuring a supply of IC wafers(or individual IC dies; see blocks 230 to 234, discussed below).

FIG. 5(A) is a top perspective view showing a PCB panel 300 (t0)provided in block 210 of FIG. 4 according to a specific embodiment ofthe present invention. FIG. 5(B) is a top perspective view showing aselected PCB 111-1 of PCB panel 300 (t0). FIGS. 6(A) and 6(B) are topperspective views showing panel 300 and selected PCB 111-1,respectively. The suffix “tx” is utilized herein to designated the stateof the PCB panel during the manufacturing process, with “t0” designatingan initial state. Sequentially higher numbered prefixes (e.g., “t1”,“t2” and “t3”) indicate that PCB panel 300 has undergone additionalprocessing.

As indicated in FIGS. 5(A) and 6(A), PCB panel 300 (t0) includes atwo-by-nine matrix of regions designated as PCBs 111, each having thefeatures described above with reference to FIG. 3(A). FIGS. 5(A) and5(B) show upper surface 116 of each PCB 111 (e.g., upper surface 116 ofpanel 111-1 includes standard USB metal contacts 121, described above),and FIGS. 6(A) and 6(B) show lower surfaces 118 of PCBs 111 (representedby PCB 111-1 in FIG. 6(B)). Note that lower surface 118 of each PCB 111(e.g., PCB 111-1) includes multiple contact pads 119-1, 119-2 and 119-3arranged in predetermined patterns for facilitating SMT and COBprocesses, as described below.

As indicated in FIG. 5(A), in addition to the two rows of PCBs 111,panel 300 (t0) includes end border regions 310 and side border regions320 that surround the PCBs 111, and a central region 340 disposedbetween the two rows of PCBs 111. Designated cut lines are scored orotherwise partially cut into PCB panel 300 (t0) along the borders ofeach of these regions, but do not pass through the panel material. Forexample, end cut lines 311 separate end border panels 310 fromassociated PCBs 111, side cut lines 321 separate side border panels 310from associated PCBs 111, and central cut lines 341 separate centralregion 340 from associated PCBs 111. PCB cut lines 331 are formed alongthe side edges between adjacent PCBs 111. The border panels are providedwith positioning holes and other features known to those skilled in theart to facilitate the manufacturing process, and are removed duringsingulation (described below).

According to an aspect of the invention, each PCB 111 of panel 300 (t0)defines a predetermined number of openings 115 that extend between uppersurface 116 and lower surface 118 (e.g., as depicted by FIGS. 5(B) and6(B)). Openings 115 are in the form of elongated slots that arepositioned behind standard USB contacts 121 (i.e., as indicated in FIG.5(B), standard USB contacts 121 are positioned between openings 115 andfront edge 111P-1 of substrate 111-1). As discussed herein openings 115are utilized in the mounting of contact springs.

Note that PCBs for USB memory cards that are produced using SMT-onlymanufacturing processes must be significantly wider than PCBs 111 due tothe space required to mount already packaged flash memory devices. Assuch, PCB panels for SMT-only manufacturing methods typically includeonly twelve PCBs arranged in a 2×6 matrix. By utilizing COB methods tomount the flash memory, the present invention facilitates significantlynarrower PCB 111, thereby allowing each PCB panel 300 (t0) to include 18PCBs 111 arranged in a 2×9 matrix. By increasing the number of PCBs 111per PCB panel, the present invention provides shorter manufacturing timeand hence lower cost.

FIGS. 7(A) to 10(B) illustrate the assembly and mounting of springassemblies onto PCB panel 300 (t0) according to an embodiment of theinvention. FIGS. 7(A) and 7(B) are exploded perspective and perspectiveviews depicting the formation of a spring assembly 120 according to anembodiment of the present invention. Spring assembly 120 includes fivesubstantially C-shaped contact springs 122 having a pair of baseportions 123 that are secured to a substrate 125, and a central contactportion 124 that forms an arched (bent) structure extending between baseportions 123 and held away from substrate 125. In one embodiment,substrate 125 is plastic or another non-conducting material), andcontact springs 122 are secured by adhesive to substrate 125 in apattern and spacing that precisely matches the pattern and spacing ofopenings 115 defined on PCB 111A (discussed above). In one embodiment,both base portions 123 are coated with low temperature (i.e.,approximately 160° C.) lead-free solder, and substrate 125 is one-sidedadhesive tape of high temperature resistance type (i.e., able to sustaintemperatures greater than 180° C.). FIGS. 8(A) and 8(B) are perspectivetop and bottom views, respectively, illustrating the subsequent processof mounting a spring assembly 120 onto PCB 111-1 of PCB panel 300 (t0)(shown in FIG. 6(B)). As indicated, spring assembly 120 is mounted ontoPCB 111-1 such that a portion of each contact spring 122 extends througha corresponding elongated slot (opening) 115. To facilitate the transferof signals between contact springs 122 and the subsequently-mounted ICdies, each contact spring 122 is electrically connected to an associatedconductive trace (not shown) formed on PCB 111-1. In one embodiment,metal pads (not shown) are disposed on each PCB 111 at both ends of eachslot 115. These pads are connected to the dual-personality communicationintegrated circuit (IC) 131 electrically (not shown) by way ofcorresponding traces. These pads are soldered to the top surface of eachbase portion 123 of each contact spring 122. FIG. 9(A) shows panel 300(t1) after spring assemblies 120 are mounted on each PCB 111 (e.g.,spring assembly 120-1 is mounted on lower surface 118 of PCB 111-1, asshown in additional detail in FIG. 9(B)). As indicated in FIGS. 10(A)and 10(B), contact portion 124 of each contact spring 122 protrudesthrough a corresponding slot 115 and extends above upper surface 116 ofeach PCB 111 (e.g., PCB 111-1).

FIG. 11(A) is a perspective view depicting a portion of panel 300 (t0)that is used to mount passive components on PCB 111-1 according to block225 of FIG. 4. During the first stage of the SMT process, lead-freesolder paste is printed on contact pads 119-3, which in the presentexample correspond to SMT components 140, using custom made stencil thatis tailored to the design and layout of PCB 111-1. After dispensing thesolder paste, the panel is conveyed to a conventional pick-and-placemachine that mounts each SMT component 140 onto a corresponding pair ofcontact pads 119-3 according to known techniques. Upon completion of thepick-and-place component mounting process, the PCB panel is then passedthrough an IR-reflow oven set at the correct temperature profile. Thesolder of each pad on the PC board is fully melted during the peaktemperature zone of the oven, and this melted solder connects all pinsof the passive components to the finger pads of the PC board. FIG. 11(B)shows PCB 111-1 of the resulting PCB panel 300 (t2), which now includespassive components 140 mounted thereon by the completed SMT process.

FIG. 12(A) is a simplified perspective view showing a semiconductorwafer 400 (t0) procured or fabricated according to block 230 of FIG. 4.Wafer 400 (t0) includes multiple ICs 430 that are formed in accordancewith known photolithographic fabrication (e.g., CMOS) techniques on asemiconductor base 401. In the example described below, wafer 400 (t1)includes ICs 430 that comprise, e.g., dual-personality communicationICs. In a related procedure, a wafer (not shown) similar to wafer 400(t1) is produced/procured that includes flash memory circuits, and in analterative embodiment (described in additional detail below), ICs 430may include both dual-personality communication ICs and flash memorycircuits. In each instance, these wafers are processed as describedherein with reference to FIGS. 12(B), 12(C) and 12(D).

As indicated in FIGS. 12(B) and 12(C), during a wafer back grind processaccording to block 232 of FIG. 4, base 401 is subjected to a grindingprocess in order to reduce the overall initial thickness TW1 of each IC430. Wafer 400 (t1) is first mount face down on sticky tape (i.e., suchthat base layer 401 (t0) faces away from the tape), which is pre-tapedon a metal or plastic ring frame (not shown). The ring-frame/waferassembly is then loaded onto a vacuum chuck (not shown) having a verylevel, flat surface, and has diameter larger than that of wafer 400(t0). The base layer is then subjected to grinding until, as indicatedin FIG. 12(C), wafer 400 (t1) has a pre-programmed thickness TW2 that isless than initial thickness TW1 (shown in FIG. 12(B)). The wafer iscleaned using de-ionized (DI) water during the process, and wafer 400(t1) is subjected to a flush clean with more DI water at the end ofmechanical grinding process, followed by spinning at high speed to airdry wafer 400 (t1).

Next, as shown in FIG. 12(D), the wafer is diced (cut apart) alongpredefined border regions separating ICs 430 in order to produce IC dies130 according to block 234 of FIG. 4. After the back grind process hascompleted, the sticky tape at the front side of wafer 400 (t1) isremoved, and wafer 400 (t1) is mounted onto another ring frame havingsticky tape provided thereon, this time with the backside of the newlygrinded wafer contacting the tape. The ring framed wafers are thenloaded into a die saw machine. The die saw machine is pre-programmedwith the correct die size information, X-axis and Y-axis scribe lanes'width, wafer thickness and intended over cut depth. A proper saw bladewidth is then selected based on the widths of the XY scribe lanes. Thecutting process begins dicing the first lane of the X-axis of the wafer.De-ionized wafer is flushing at the proper angle and pressure around theblade and wafer contact point to wash and sweep away the silicon sawdust while the saw is spinning and moving along the scribe lane. Thesawing process will index to the second lane according to the die sizeand scribe width distance. After all the X-axis lanes have beencompleted sawing, the wafer chuck with rotate 90 degree to align theY-axis scribe lanes to be cut. The cutting motion repeated until all thescribe lanes on the Y-axis have been completed.

FIG. 13(A) is a perspective view depicting a die bonding processutilized to mount IC dies 131 and 135 on PCB 111-1 of the PCB panel 300(t2) (described above with reference to FIG. 11(B)) according to block240 of FIG. 5. The die bonding process generally involves mounting ICdies 131 into lower surface region 118A, which is surrounded by contactpads 119-1, and mounting IC die 135 into lower surface region 118B,which is surrounded by contact pads 119-2. In one specific embodiment,an operator loads IC dies 131 and 135 onto a die bonder machineaccording to known techniques. The operator also loads multiple PCBpanels 300 (t2) onto the magazine rack of the die bonder machine. Thedie bonder machine picks the first PCB panel 300 (t2) from the bottomstack of the magazine and transports the selected PCB panel from theconveyor track to the die bond (DB) epoxy dispensing target area. Themagazine lowers a notch automatically to get ready for the machine topick up the second piece (the new bottom piece) in the next cycle of diebond operation. At the die bond epoxy dispensing target area, themachine automatically dispenses DB epoxy, using pre-programmed writepattern and speed with the correct nozzle size, onto the target areas118A and 118B of each of the PCB 111 of PCB panel 300 (t2). When allPCBs 111 have completed this epoxy dispensing process, the PCB panel isconveyed to a die bond (DB) target area. Meanwhile, at the input stage,the magazine is loading a second PCB panel to this vacant DB epoxydispensing target area. At the die bond target area, the pick up armmechanism and collet (suction head with rectangular ring at theperimeter so that vacuum from the center can create a suction force)picks up an IC die 131 and bonds it onto area 118A, where epoxy hasalready dispensed for the bonding purpose, and this process is thenperformed to place IC die 135 into region 118B. Once all the PCB boards111 on the PCB panel have completed die bonding process, the PCB panelis then conveyed to a snap cure region, where the PCB panel passesthrough a chamber having a heating element that radiates heat having atemperature that is suitable to thermally cure the epoxy. After curing,the PCB panel is conveyed into the empty slot of the magazine waiting atthe output rack of the die bonding machine. The magazine moves up oneslot after receiving a new panel to get ready for accepting the nextpanel in the second cycle of process. The die bonding machine willrepeat these steps until all of the PCB panels in the input magazine areprocessed. This process step may repeat again for the same panel forstack die products that may require to stacks more than one layer ofmemory die. FIG. 13(B) is a top perspective views showing PCB 111-1 ofPCB panel 300 (t3) after the die bonding process is completed.

FIG. 14(A) is a perspective view depicting a wire bonding processutilized to connect the IC dies 131 and 135 to corresponding contactpads 119-1 and 119-2, respectively, according to block 245 of FIG. 4.The wire bonding process proceeds as follows. Once a full magazine ofPCB panels 300 (t3) (see FIG. 13(B)) has completed the die bondingoperation, an operator transports the PCB panels 300 (t3) to a nearbywire bonder (WB) machine, and loads the PCB panels 300 (t3) onto themagazine input rack of the WB machine. The WB machine is pre-preparedwith the correct program to process this specific EUSB memory card. Thecoordinates of all the ICs' pads 119-1 and 119-2 and PCB gold fingerswere previously determined and programmed on the WB machine. After thePCB panel with the attached dies is loaded at the WB bonding area, theoperator commands the WB machine to use optical vision to recognize thelocation of the first wire bond pin of the first memory die of the firstPCB on the panel. Once the first pin is set correctly, the WB machinecan carry out the whole wire bonding process for the rest of the panelsof the same product type automatically. For multiple flash layer stackdies, the PCB panels may be returned to the WB machine to repeat wirebonding process for the second stack. FIG. 14(B) is a top perspectiveviews showing PCB panel 300 (t4) after the wire bonding process iscompleted.

FIGS. 15(A) and 15(B) are simplified cross-sectional side viewsdepicting a molding process for forming a molded housing layer over PCBpanel 300 (t4) according to block 250 of FIG. 4. As indicated in FIG.15(A), after the wire bonding process is completed, USB panel 300 (t4)is loaded into a mold machine 450 including a cover plate 452 thatmounts onto lower surface 116 of PCB panel 300 (t4), and defines achamber 456 that is disposed over the IC chips, wire bonds and passivecomponents that are mounted on lower surface 116 of each PCB. Note thatno molding material is applied to upper surface 118. Transfer molding isused due to the high accuracy of transfer molding tooling and low cycletime. The molding material in the form of pellet is preheated and loadedinto a pot or chamber (not shown). As depicted in FIG. 15(B), a plunger(not shown) is then used to force the material from the pot throughchannels known as a spruce and runner system into the mold cavity 456,causing the molten (e.g., plastic) material to form molded casings 150over each PCB that encapsulates all the IC chips and components, and tocover all the exposed areas of upper surface 116. Note that substrates125 cover openings 115, thereby preventing molten plastic from enteringopenings 115 and forming on contact springs 122, which could preventelectrical connection when inserted into a host female socket. The moldremains closed as the material is inserted and filled up all vacant incavity 456. During the process, the walls of cover plate 452 are heatedto a temperature above the melting point of the mold material, whichfacilitates a faster flow of material through cavity 456. Mold machine450 remains closed until a curing reaction within the molding materialis complete. A cooling down cycle follows the injection process, and themolding materials of molded casings 150 start to solidify and harden.Ejector pins push PCB panel 300 (t5) (shown in FIG. 15) from the moldmachine once molded casings 150 has hardened sufficiently over the PCBs(e.g., housing 150-1 on PCB 111-1).

FIG. 17 is simplified cross-sectional side view depicting a singulationprocess according to block 260 of FIG. 4 that is used to separate PCBpanel 300 (t5) into individual sub-assemblies 101A. PCB panel 300 (t5)is loaded into a saw machine (not shown) that is pre-programmed with asingulation routine that includes predetermined cut locations. The sawblade is aligned to the first cut line (e.g., end cut line 311-1) as astarting point by the operator. The coordinates of the first positionare stored in the memory of the saw machine. The saw machine thenautomatically proceeds to cut up (singulate) the USB pane 300 (t5), forexample, successively along cut lines 311-1, 341-1, 341-2, and 311-2,and then along the side cut lines and PCB cut lines (see FIG. 5(A)) toform individual sub-assemblies 101A, which are shown and described abovewith reference to FIGS. 3(A) and 3(B), according to the pre-programmedsingulation routine.

Referring to block 280 located at the bottom of FIG. 4, final proceduresin the manufacturing method of the present invention involve optionalmarking (block 270), testing, packing and shipping the individualextended USB memory cards. An exemplary marked EUSB memory card 101A isshown in FIG. 18, including company name and country of manufactureprinted on upper surface 116. Additional information, such as memorysize (storage capacity), lot number and manufacturing date may beprinted, e.g., on lower surface 152 of plastic molded housing 150 (i.e.,opposite to upper surface 116). Visually or/and electrically testrejects are removed from the good population as defective rejects. Thegood extended USB memory cards are then packed into custom made boxeswhich are specified by customers. The final packed products will shipout to customers following correct procedures with necessary documents.

FIG. 19 is a block diagram showing a simplified dual-purpose controller130-2 according to another embodiment of the present invention. CPU 710communications with a dual-personality transceiver 720 by way of aninternal bus 740. Dual-personality transceiver 720 operates in a mannersimilar to that described above with reference to host system 105 (FIG.2) to communicate with both standard USB contact pads 121 and extendedpurpose contact springs 122 in order to communicate with a host system,e.g., by way of socket 190 (see FIG. 2). Note that controller 130-2includes a memory controller 750 for controlling read/write operationsto flash memory circuits that are part of the PCBA hosting dual-purposecontroller 130-2, thereby facilitating the dual-personality (i.e.,EUSB-type and USB-type) communications that are described above.

FIG. 20 is simplified cross-sectional side view showing a stacked-memoryEUSB memory card 101-2 in which dual-purpose controller 130-2 accesses afirst flash memory chip 535-1 and a second flash memory chip 535-2.First flash memory chip 535-1 is mounted on a lower surface 118 of a PCB111-2 and connected by first wire bonds 560-1 to PCB 111-2 in the mannerdescribed above. Because the IC die height (thickness) D is much smallerthan packaged flash memory devices, and because the thickness T1 of EUSBmemory card 500 is set, for example, at 2.0 mm to assure a snug fit ofthe extended USB memory card inside a female USB socket (e.g., socket190, shown in FIG. 1(A)), the present invention facilitates a stackedmemory arrangement in which second flash memory die 535-2 is mounted onfirst flash memory die 535-1 and connected to PCB 111-2 by way of secondwire bonds 560-2. In an alternative embodiment (not shown), second flashmemory die 535-2 may be connected to contacts provided on first flashmemory die 535-1 by associated wire bonds. This stacked memoryarrangement greatly increases memory capacity of the extended USB memorycards without increasing the footprint (i.e., thickness T1, length andwidth) of EUSB memory card 101-2. EUSB memory card 101-2 is thenprocessed and assembled as described above to produce a correspondingcompleted extended USB memory card.

FIG. 21 is simplified cross-sectional side view showing a EUSB memorycard 110-3 including stacked-memory according to another embodiment ofthe present invention. EUSB memory card 110-3 is distinguished over theprevious embodiments in that, instead of separate controller and flashmemory chips, EUSB memory card 110-3 utilizes a single-chip dual-purposecontroller/flash die 630 that is connected to a PCB 111-3 by way of wirebonds 660 in the manner described above, and is characterized in thatsingle-chip dual-purpose controller/flash die 630 includes both adual-purpose controller circuit and one or more flash block mass storagecircuits that are interconnected by a bus.

FIGS. 22 to 25 depict an extended Universal-Serial-Bus (EUSB) assembly700 according to another specific embodiment that utilizes EUSB memorycard 101A (described above) as a modular structure that is fixedlyconnected inside an external plastic case such that, as indicated inFIG. 23, both the fixed metal contacts and contact springs (not shown)of EUSB memory card 101A are accessible through a front opening 735defined by a standard USB metal plug shell 730 of case 710.

Referring to FIG. 22, in addition to EUSB memory card 101A and standardUSB metal plug shell 730, the assembly 700 includes a cylindrical body710, a plug structure 720, an elastic loop (e.g., a rubber band) 740,and a cap 750. Cylindrical body 710 is a molded plastic structureincluding a cylindrical section 712 having an open front end 715 and aclosed rear end (not shown), and also includes several (e.g., four)recesses 713 defined on the inside wall of cylindrical section 712. Plugstructure 720 includes a front end plate 711, a cylindrical base 722having an open rear side (not shown) that communicates with an opening715, and a plug support frame 716 extending from front end plate 711.Cylindrical base 722 includes four protrusions 723 and a pole 724. Plugsupport frame 716 includes protrusions 717 that mate with openings 737formed on standard USB metal plug shell 730.

Assembly 700 is assembled as follows. The front end of EUSB memory card101A is inserted into opening 715 of plug structure 720 from the rearside, and elastic loop 740 is looped over pole 714 such that most ofelastic loop 740 is positioned in front of end plate 721. The rear endof EUSB memory card 101A and plug structure 720 are then inserted intoopen front end 715 of cylindrical body 710 until cylindrical base 722 isreceived therein, and then cylindrical base 722 is turned untilprotrusions 723 snap into recesses 713 defined in cylindrical section712. Standard USB metal plug shell 730 is then mounted over plug supportframe 716 and secured to plug structure 720 by snapping protrusions 717of plug support frame 716 into openings 737 formed on standard USB metalplug shell 730. The sub-assembly including EUSB memory card 101A,cylindrical body 710, plug structure 720, standard USB metal plug shell730, and elastic loop 740 is shown in FIG. 23. Note that the contactpads and contact springs of EUSB memory card 101A (described above) areaccessible through front opening 735 of metal plug shell 730.

Referring to FIG. 24, cap 750 is a molded plastic structure includingtwo components: a cylindrical cap base 752 and a tuning fork-typeretainer 756 for securing elastic loop 740 (partially shown).Cylindrical cap base 752 defines an upper slot 755-1 for receivingretainer 756 and a lower slot for receiving the plug portion of thesub-assembly shown in FIG. 23 (discussed above). Tuning fork-typeretainer 756 includes a base structure 757 having two prongs that snapcouple to corresponding structures (not shown) disposed in upper slot755-1, and a hook structure 758 for holding the free end of elastic loop740. During assembly, elastic loop 740 is mounted over hook structure758, and then tuning fork-type retainer 756 is pushed into and snapcoupled to cylindrical cap base 752. Cap 750 is then fitted over thefront end of the sub-assembly shown in FIG. 23 to form the final EUSBassembly 700, shown in FIG. 25.

Although the present invention has been described with respect tocertain specific embodiments, it will be clear to those skilled in theart that the inventive features of the present invention are applicableto other embodiments as well, all of which are intended to fall withinthe scope of the present invention. For example, although the presentinvention is described with specific reference to nine-pin extended USBmemory cards, the present invention is also applicable to other EUSBdevices, and using other extended USB communication systems (i.e.,including a number of contact springs 122 other than five, as disclosedherein).

1. An extended Universal-Serial-Bus (EUSB) device comprising: a printedcircuit board assembly (PCBA) including: a printed circuit board (PCB)including a front edge, the PCB having opposing first and secondsurfaces and defining a plurality of openings extending between theopposing first and second surfaces and located adjacent to the frontedge, a plurality of metal contact pads disposed on the first surface ofthe PCB and located between the front edge and the plurality ofopenings, a plurality of metal contact springs, each metal contactspring extending through a corresponding opening of said plurality ofopenings such that a contact portion of said each metal contact springprotrudes from said first surface; at least one passive componentmounted on the second surface of the PCB handle section; and at leastone integrated circuit (IC) mounted on the second surface of the PCBhandle section; and a single-piece molded housing formed on the secondsurface of the PCBA such that said at least one passive component andsaid at least one IC are covered by said molded housing, and such thatsubstantially all of the first surface of the PCB is exposed.
 2. TheEUSB device of claim 1, wherein each of the plurality of metal contactsprings comprises a pair of base portions that are secured to asubstrate, and said contact portion comprises a bent structure extendingbetween the pair of base portions.
 3. The EUSB device of claim 1,wherein the molded housing includes a planar surface extending parallelto the PCB and extends from the PCB handle section to the PCB plugsection, and wherein a first thickness measured between the firstsurface of the PCB and the planar surface adjacent to the metal contactsis substantially equal to a second thickness between the first surfaceof the PCB and the planar surface adjacent to the IC die.
 4. The EUSBdevice of claim 3, wherein the first thickness is in the range of 2.3 to2.5 mm.
 5. The EUSB memory card of claim 3, wherein the molded housingincludes a peripheral wall extending perpendicular to the planarsurface, and wherein the peripheral wall is aligned with a peripheraledge of the PCB.
 6. The EUSB device of claim 1, wherein the at leastwherein said at least one IC comprises at least one unpackaged IC diethat is electrically connected to the conductive traces by a pluralityof wire bonds extending between said at least one unpackaged IC die andcorresponding contact pads disposed on the second surface of the PCB. 7.The EUSB device of claim 6, wherein the at least one passive componentincludes a lead that is soldered to a corresponding contact pad disposedon the second surface of the PCB.
 8. The EUSB device of claim 6, whereinthe at least one integrated circuit (IC) die includes a first IC diecomprising an EUSB controller circuit, and a second IC die comprising aflash memory circuit.
 9. The EUSB device of claim 8, wherein the atleast one integrated circuit (IC) die comprises a plurality of flashmemory dies disposed in a stacked arrangement such that a first flashmemory die is mounted on the second surface of the PCB, and a secondflash memory die is mounted on a surface of the first flash memory die.10. The EUSB device of claim 9, wherein the first flash memory die isconnected to said PCB by a first plurality of said wire bonds, and thesecond flash memory die is connected to one of the first flash memorydie and said PCB by a second plurality of wire bonds.
 11. The EUSBdevice of claim 6, wherein the at least one integrated circuit (IC) dieincludes a single-chip controller/flash die comprising controllercircuit and one or more flash block mass storage circuits that areinterconnected by a bus.
 12. An assembly comprising: an extendedUniversal-Serial-Bus (EUSB) device including: a printed circuit boardassembly (PCBA) including: a printed circuit board (PCB) including afront edge, the PCB having opposing first and second surfaces anddefining a plurality of openings extending between the opposing firstand second surfaces and located adjacent to the front edge, a pluralityof metal contact pads disposed on the first surface of the PCB andlocated between the front edge and the plurality of openings, aplurality of metal contact springs, each metal contact spring extendingthrough a corresponding opening of said plurality of openings such thata contact portion of said each metal contact spring protrudes from saidfirst surface; at least one passive component mounted on the secondsurface of the PCB handle section; and at least one integrated circuit(IC) mounted on the second surface of the PCB handle section; and asingle-piece molded housing formed on the second surface of the PCBAsuch that said at least one passive component and said at least one ICare covered by said molded housing, and such that substantially all ofthe first surface of the PCB is exposed; and a case fixedly connected tothe EUSB device such that the fixed metal contacts and the contactsprings are accessible through a front opening defined by said case. 13.The assembly of claim 12, wherein each of the plurality of metal contactsprings comprises a pair of base portions that are secured to asubstrate, and said contact portion comprises a bent structure extendingbetween the pair of base portions.
 14. A method for producing anextended Universal-Serial-Bus (EUSB) device comprising: producing aprinted circuit board (PCB) including opposing first and secondsurfaces, a plurality of metal contacts disposed on the first surface, aplurality of first contact pads disposed on the second surface, aplurality of second contact pads disposed on the second surface, and aplurality of openings defined through the PCB; mounting a plurality ofcontact springs onto the PCB such that each contact spring extendsthrough a corresponding opening of said plurality of openings, and suchthat a contact portion of each contact spring protrudes above the firstsurface of said PCB; attaching at least one integrated circuit (IC) tothe first contact pads and at least one passive component to the secondcontact pads; and forming a single-piece molded housing on the secondsurface of the PCB such that said at least one passive component andsaid at least one IC die are covered by said molded housing, and suchthat substantially all of the first surface of the PCB is exposed. 15.The method of claim 14, wherein mounting said plurality of contactsprings comprises attaching base portions of each of said plurality ofcontact springs to a substrate, and then mounting said substrate ontothe second surface of the PCB such that said contact portions protrudeabove the first surface, and such that the substrate covers theplurality of openings.
 16. The method of claim 14, wherein attachingsaid at least one IC and said at least one passive component comprises:attaching said at least one passive component to the first contact padsusing a surface mount technique; die bonding at least one unpackaged ICdie to the second surface of the PCB, and then wire bonding said atleast one unpackaged IC die to said first contact pads using achip-on-board technique.
 17. The method of claim 16, wherein attachingsaid at least one passive component further comprises: printing a solderpaste on said first contact pads; mounting said at least one componenton said first contact pads; and reflowing the solder paste such thatsaid at least one component is fixedly soldered to said first contactpads.
 18. The method of claim 16, further comprising grinding a waferincluding said at least one IC die such that a thickness of said waferis reduced during said grinding, and then dicing said wafer to providesaid at least one IC die.